As far as I know, the only evidence of integument in sauropodomorphs is a few patches of skin impressions, so we know that at least some of them had scales over part of their body. However, as both ornithichians and theropods are known to have filament-like structures, they are also possible in sauropodomorphs.

Beautiful work. Maybe your herrerasaurid depictions have already worked their way into the minds of some dA guys more than they... er ... we'd like to admit - for example, check out <a wytiwyg="1" href="smnt2000.deviantart.com/>Smnt2k's or my drawings.